In recent years, for controlling the flow of traffic, various barrier systems consisting of large sections of precast concrete have been used along highways. The sections can be hoisted into place and removed with greater speed and ease than is usually required to construct more permanent structures. Systems of this type can be dislodged when sufficient external force is applied, resulting in a potential traffic hazard. In some instances, the concrete sections are bolted together to maintain their alignment and assure that they will not be either knocked over or displaced by a colliding vehicle. However, such systems have the disadvantage of being complex and expensive and require considerable time and effort to assemble as well as to remove without disassembling the entire structure when used in road repairs.
Improvements in the system of bolted connections has been the use of looped steel bars that allow for a straight steel pin connection holding the adjoining loops together. This system is expensive and relies on maintaining the pins which also requires one's hands in a dangerous position between the barrier sections during placement or replacement. Vehicle impact on these systems usually requires significant time and expense to remove the pins.
U.S. Pat. No. 5,149,224 to Smith, which is herein incorporated by reference, shows an interlocking highway structure which employs a pair of “J” shaped hooks that connect separate concrete barrier members together without requiring extra hardware. In practice, the end of one precast concrete member is simply slid downward from the top such that the two adjoining precast concrete members have interlocking J connections. The product is commercially marketed as “JJ Hooks®”. The JJ Hooks product includes a short, approximately 10 inches in length, member to which rebar members are welded and extend inward into the precast concrete. While FIG. 3 of U.S. Pat. No. 5,149,224 shows the rebar extending only part way into the precast concrete, in practice the rebar can extend end-to-end with weldment of the rebar to both attachment hooks or can extend only part way into the precast concrete based on steel shear analysis.
Modifications to the JJ Hooks® design would be beneficial in order to address newer crash test criteria and to allow for greater use of the concrete barriers.